A double-swirl spray nozzle of this type is known from the DE 100 33 781 C1. Nozzles of this type are utilized in particular, as also other double-swirl spray nozzles according to the DE 197 58 526 A1, mainly for so-called gas washers, where a washing liquid is supplied over a plurality of spray nozzles distributed as evenly as possible in the gas flow over the cross section of the conduit therefor. Such gas washers may, for example, be flue-gas cleaning systems, where sour flue-gas parts like sulfur dioxide, chlorine or hydrogen fluoride and to a small degree also flue-gas dust are separated with the use of suitable washing liquids. The advantage of the above-mentioned double-swirl nozzles is thereby that the swirling action of the supplied washing liquid is mutually cancelled so that an undesired influence on the flow in the gas washer can be avoided. This results in a higher efficiency.
The nozzles in such gas washers are distributed over several planes, whereby the gas in the gas washers flows usually from below upwardly and the atomized medium falls downwardly, thus against the gas flow. The aforementioned double-swirl spray nozzles according to the DE 100 33 781 C1 are utilized in the lower area, whereas in the upper area eccentric nozzles spraying only to one side, thus downwardly are provided in order to avoid that spraying into the droplet separator provided at the upper end of gas washers, in particular flue-gas desulfurizing systems, occurs.
Such eccentric nozzles have as a rule the following disadvantages: Since often the same volume flow as in the double-swirl spray nozzles in the lower area is desired, same must now be sprayed through a swirl chamber (mouth piece); this coarsens the droplet spectrum, which can have a negative affect on the process. If one wants to maintain the droplet spectrum constant and therefore cut the volume flow per nozzle in half, then one must place twice as many nozzles, which can result in high costs (fastening means, installation, pipe connections). Since the swirl direction of all eccentric nozzles is the same, a swirl acts on the gas flow, which, as above indicated, can have a negative affect on the cleaning process.
The purpose of the invention is to provide a double-swirl spray nozzle of the above-identified type in such a manner that a spray jet is possible only to one side in spite of a swirl cancellation and yet enabling a large surface to be covered with the spray jets.
To attain this purpose it is provided that both swirl chambers are open to the same side. It has thereby been surprisingly discovered that in this case, due to the common supply channel for the side-by-side lying swirl chambers, already shortly after an exiting of the medium from the swirl chambers mutually overlapping spray jets do not lead to any disadvantageous formation of the spray fan being created. Since the droplets of the directly adjacent atomizing cones being created hit one another quasi unstopped due to the small spacing between the swirl chambers, the oppositely directed radial speed of the droplets results in such an impact that the droplets burst open and thus the droplet spectrum becomes finer. This effect indeed also exists in traditionally arranged nozzles having a spacing of 700 to 1200 mm from one another, however, because of the radial speed being slowed down by the air resistance, the effect is no longer so distinct. Therefore, a droplet spectrum is created by the invention which contributes to an improved efficiency. Since the swirl chambers themselves must be designed only for half of the volume flow, the length of, and thus also the moments acting onto, the nozzle connection can be reduced. The axes of the swirl chambers extend at an angle to one another and diverge toward the outlet openings. This embodiment enables an enlargement of the surface covered by the spray jets. The danger of untreated gas moving through the washer is thus reduced. The new double-swirl spray nozzle is very compact and efficient. It has been shown that when the angle of adjustment of the axes of the swirl chambers is approximately 20°, a particularly advantageous spray-jet formation can be achieved.